


pouched eggs

by armethaumaturgy



Series: Reqs [2]
Category: Undertale (Video Game)
Genre: Alternate Universe - The Little Mermaid Fusion, Biting, Cloaca, Cross (X-tale) - Freeform, Eggpreg, Explicit Sexual Content, Hemipenes, Killer (Killertale) - Freeform, Killer/Cross - Freeform, M/M, Mating Cycles/In Heat, Multiple Orgasms, Nightmare (Dreamtale) - Freeform, Non-Human Genitalia, Oviposition, kross - Freeform
Language: English
Status: Completed
Published: 2021-02-11
Updated: 2021-02-11
Packaged: 2021-03-18 06:41:36
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,575
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29364171
Author URL: https://archiveofourown.org/users/armethaumaturgy/pseuds/armethaumaturgy
Summary: Cross set his weapon and the sharpening rock aside, pointedly looking away from Killer the second his scent hit him at full force from the proximity. “Would you like me to wake up one of the others?” he asked, feeling a flush coloring his cheekbones. He hadn’t realized the mating season was upon them, but Killerreekedof pheromones, and it was making Cross’ marrow boil in his bones.Killer pretended to think about it, but there was a glint in his sockets as they narrowed. “Nah. How about it, little guard?”
Relationships: Sans/Sans (Undertale)
Series: Reqs [2]
Series URL: https://archiveofourown.org/series/2151672
Comments: 23
Kudos: 261





	pouched eggs

**Author's Note:**

  * For [Starfyll](https://archiveofourown.org/users/Starfyll/gifts).



> based on [skumhuu's](https://archiveofourown.org/users/skumhuu/pseuds/skumhuu) leviathan au!  
> this is for [starfyll](https://twitter.com/Starfyll) on twitter! ♥  
> and a thanks to [avosettas](https://twitter.com/avosettas) for the title again haha♥

Cross was sharpening his knife by the rock on the edge of the cove, eyesockets peered for any potential threats as the stone he was using clinked against the blade. That was the only reason he’d noticed Killer stirring from the pile everyone had fallen asleep in, encircled by one of Nightmare’s tentacles.

The scent hit him a second later, heady and thick in the water. Killer moved so fast that if Cross hadn’t been looking his way, he would’ve missed it. The other shark propped himself on the edge of his rock, fin flaring. Cross didn’t know it was even possible, but his sockets looked hazy.

“Criss-cross,” Killer drawled, pulling his torso closer. His claws were leaving indents in the rock.

Cross set his weapon and the sharpening rock aside, pointedly looking away from Killer the second his scent hit him at full force from the proximity. “Would you like me to wake up one of the others?” he asked, feeling a flush coloring his cheekbones. He hadn’t realized the mating season was upon them, but Killer _reeked_ of pheromones, and it was making Cross’ marrow boil in his bones.

Killer pretended to think about it, but there was a glint in his sockets as they narrowed. “Nah. How about it, little guard?” He was close enough that it was easy for him to reach out and trail a claw over Cross’ pelvis, igniting a line across his scales. “You’d look so good carrying a clutch.”

Cross shivered; he was ashamed to say both Killer’s scent and words were getting to him. Unused to such advances as he was, it probably wasn’t all that surprising. A proposition like this was miles from hiding in a dark nook to wait the season out with just his hands for company. There was also the unspoken implication that Killer could have chosen anyone from the shiver, yet he came to _Cross_.

An involuntary chirrup left him, and Killer’s grin widened at the obvious acquiescence.

He moved again, in front of Cross with a single swipe of his tail, and his hands immediately found their way to bones and scales alike. One trailed over his ribs, pulling out another whining chirrup, while the other went to Cross’ pouch, claws skirting the already raised edges. Cross would’ve felt ashamed about how _easy_ he was, if his mind wasn’t swimming from the heady mix of sensations and Killer’s scent, almost too strong as it filled his fake lungs.

He knew Killer wasn’t the one to dawdle, but the first claw sinking into his pouch still caught Cross off guard. It thrust shallowly into the sensitive walls, to coax his cocks out. And it was doing a great job at it, too, because moments later, at Cross’ high-pitched whine, he had to pull it out to let the lengths out in a flood of viscous slick.

And then it was right back, followed by another, and stretching the pouch with scissoring motions. Cross shivered, arching into the thrusts as his tail writhed. Killer’s free hand had taken to gripping his hip, to make it a little easier.

“You’re gonna look so good with my clutch,” Killer repeated. It almost sounded like he was talking to himself, and Cross simply happened to overhear him. “Round and pretty with all the eggs…”

Cross whined again when the fingers were pulled out, the sound transforming into a gasp when he felt one of Killer’s hemipenes rubbing along the sensitive flesh.

“Think you can take both, Criss-cross?” Killer asked, though he only pushed the lower one in. His answer was a keen and Cross’ claws scratching across his back. He laughed, pushing in with jerky thrusts as far as Cross’ body allowed him. Cross' walls were hot and clasping down on him in the best of ways and his slack-jawed expression was just a bonus.

Killer’s pace was fast and wild, and if Cross didn’t know any better, he wouldn’t believe his heat had _just_ started. His scent was all-encompassing. Cross’ head spun, spine tingling as pleasure shot up his vertebrae in bursts.

Killer nuzzled his neck, teeth barely skirting the sensitive bones and Cross could feel the reverberations of his chirp, sending another body-wracking shiver through him.

“Oh, little guard,” he whispered, the usual teasing tone accompanying the nickname foregone in favor of something softer, “You’ll be so pretty.” His soft tone was offset by the way he gripped at Cross’ hips, no doubt leaving behind marks that would stay there for days to come. “And when you’re carrying a clutch, we’ll get to protect _you_ for once.”

Cross almost screamed, his mind immediately full of the images Killer described, his stomach full of eggs and the whole shiver scrambling around him to make sure he had everything and anything he could ever want, soft touches and all the food he could never eat on his own. He had to admit the fantasy tempted him, something he’d never even dreamed of now within his grasp. He was so lost in his own head that he almost missed the way Killer’s cock swelled, the first egg travelling up the length as he stilled for a moment.

Cross whined as it stretched his pouch. Killer distracted him with a kiss, their tongues meshing together messily. It sent almost as strong pulses of pleasure through him as the way his cocks dragged across the other’s abdomen, sometimes catching Killer’s in-between them.

The first egg popped inside of him, setting in his stomach as Killer started moving anew. “You’re doing so well,” he slurred, moving back to Cross’ neck as if he was drawn there. “Can I?”

Cross craned his head to the side on instinct, before he could even process the question in its entirety. Killer made a sound so unlike him that Cross was momentarily stunned; a soft, reverent sort of a chirp.

His teeth sunk into Cross’ vertebrae, at the same time two more eggs travelled up to join the first one. The scent of marrow joined Killer’s heat. Cross’ eyelights shrunk and he held the other as close as was physically possible, digging his claws into his shoulder blades.

The sharp pain from the bite and the pleasure of the eggs settling in him one by one was too much for him to bear as his first cock came, splattering the viscous cum between the two of them. It only seemed to spur Killer on, his thrusts shallow and irregular. Cross lost count of the eggs as they filled him up.

“Fuck,” Killer muttered, tongue gingerly lapping over the bite and licking up the leaking marrow. “I can’t believe I got to mark you first. You’ll look so good with everyone’s bites, I can’t wait to see it.”

Cross made a non-cohesive trill back at him, body set ablaze. His stomach felt so heavy, and when he looked down between them, he could see it bulging out with the sheer amount of eggs, and the sight alone made him groan. At one point, Killer had twined his tail with Cross’ and they were so close, closer than Cross had ever been to anyone.

“Fuck, you look _so_ good,” Killer was babbling, even as he pulled out, much to Cross’ vocal confusion and dismay. He felt sluggish, and held like he was, he couldn’t even move. Killer shushed him with gentle sounds, his thumbs rubbing circles into his hips. “Just a lil more, Criss-cross.”

He thrust in again, this time with his other cock. Cross’ cry was visualized with a slew of bubbles, trailing off into a long groan when Killer started up a pace that left him gasping for breath he couldn’t regain. His cock dragged across his walls in the best of ways, a coil in Cross’ bloated stomach winding tighter and tighter.

“Kill—” he cried, cutting himself off with a moan. The coil snapped and his other hemipene had come as well, adding to the mess between them.

“Fuck, fuck, _fuck_ —” Killer replied, dark sockets watching as he fell apart. His rhythm stuttered and he only managed a handful of thrusts before he was coming as well, making Cross cry out once more.

Every single free crevice in him was filled with Killer’s cum, stomach distending further to accommodate it. He felt weightless as Killer pulled out, his lengths retreating back into his pouch to seal everything in.

And yet he also felt so heavy, unused to carrying a clutch. Killer kissed him again, until his head cleared of the post-orgasmic haze. He felt drowsy and couldn’t even bring himself to respond to the tongue probing his mouth, but Killer didn’t seem to mind.

Something wrapped around his wrist and tugged him towards the still-sleeping shiver. Cross thought it was simply Killer, until he noticed the glowing cyan of Nightmare’s eye watching them. His face flushed, but he couldn’t find anything to say, especially since the kraken didn’t comment on anything that had just transpired.

He was pulled into the pile along with the other shark, urged to curl in the very middle of it, where the other one had been before. Killer took another spot, content to curl around Dream’s back.

The last thing Cross was aware of before sleep overtook him was Nightmare’s tentacle curling around him almost protectively, its tip trailing across the bulge of his stomach. His clutch.

For once, Cross was happy to let himself feel protected.

**Author's Note:**

> find me on twitter @esqers ♥♥


End file.
